You must place them in their rightful spots on the big Music Box, located in the Lobby. There will be three indentations with an engraving next to each. Read the descriptions to figure out which box goes where. You will need to know your stories in order to solve this puzzle -- or read below for the solutions.

After setting all three in the correct spots, play the music box. The piece that holds all the music boxes will rotate in a circle. Investigate the front music box to claim the Hotel Stairway Key.